Suburban Democrats are bracing to defend their recent gains amid unmistakable signs of volatility among an electorate that is impatient with the pace of economic recovery.

Their concerns are coming into sharp focus amid ongoing developments in Nassau County, N.Y., where County Executive Tom Suozzi, a rising star in New York politics and a prominent suburban Democratic politician, might lose his seat in a recount.

Suozzi’s predicament comes on the heels of other troubling developments in some of the nation’s largest suburban counties, including nearby Democratic Westchester County, where voters tossed out County Executive Andrew Spano in a startling upset Nov. 3.

Lawrence Levy, who directs the National Center for Suburban Studies at Hofstra University, on Long Island, said Nassau County voters were driven to the polls to reject local taxes that put additional pressure on their already strained family budgets.

“These are people who aren’t used to being economically insecure. They’re not used to thinking in terms of losing their homes,” Levy said. “Democrats have held on for a long time, but now it looks like voters are willing to give Republicans a chance. Nobody owns the suburbs anymore.”

That sentiment applied up and down the East Coast in the 2009 off-year elections, as suburbanites registered their discontent by rejecting Democratic incumbents, even in typically blue-tinted counties.

Across the Hudson River, in New Jersey, Democratic Gov. Jon Corzine lost his reelection bid, and his Republican opponent came within striking distance of victory in suburban Bergen County, a Democratic area and the largest county in the state. Gov.-elect Chris Christie also bested Corzine in Middlesex County, a suburban bellwether that President Barack Obama won by 22 points in 2008.

In the Virginia governor’s race, the news for Democrats was hardly better: Republican Bob McDonnell trounced Democrat Creigh Deeds in nearly every suburban Northern Virginia county that supported Obama last year. The only holdouts, Arlington County and the city of Alexandria, were the closest municipalities to Washington.

Some candidates already hitting the trail for 2010 say the worst may be yet to come, as voters grow frustrated with the sputtering economy and wary of the Democratic Party’s domestic agenda.

“There’s this sense that we didn’t give you a mandate, Democrats, but we gave you an opportunity to handle the situation, and it’s still pretty tough,” said Democratic Rep. Joe Sestak, who represents suburban Philadelphia and is pursuing a bid for Senate in 2010. “Hope’s not a strategy, and, therefore, they want to see results.”

Two counties in Sestak’s district, Delaware and Chester — linchpins of recent Democratic victories in the state — gave the party reason for concern earlier this month when they voted strongly for the largely anonymous Republican candidate in a state Supreme Court race just a year after giving Obama wide victory margins.

In counties like these, according to Sestak, moderate and conservative-leaning independents are particularly unnerved by a sense that Washington’s plans for economic recovery seem to be working slowly, if at all.

“There’s no such thing as a shovel-ready job. We oversold things,” Sestak said in a phone interview from York County, where he was participating in an event with veterans over the weekend.

Democrats offer a host of explanations for their weak performance in the suburbs this year: Off-year elections favor the opposition party, turnout was low in many of these races, several candidates put in especially weak performances on the stump.

Asked about the Supreme Court race in his state, Pennsylvania Gov. Ed Rendell cautioned not to “draw too many inferences” from an off-year election for a relatively obscure office.

“Republicans turned out more — as they always do, in greater percentages — in the suburbs, as they did across the state,” he said, predicting a different outcome next year, when higher-profile offices are at stake. “In 2010, with governor and senator, big turnout. It will be 2006 all over again, in my judgment.”

But Rendell, who won the historically Republican Philadelphia suburbs by large margins in the 2002 and 2006 governor’s races, said it would stand to reason that restive suburban voters might be more vulnerable to persuasion than other, more-partisan constituencies.

“Suburban voters tend to be independent, intelligent, and they listen and they make up their minds,” Rendell said. “They would take a chance on Chris Christie rather than electing Jon Corzine. McDonnell ran a much better campaign than Deeds did.”

While few would dispute that Deeds was outmatched as a candidate, Republican pollster Glen Bolger, who worked on McDonnell’s campaign, said suburban Virginia voters were responding to the national environment, too.

“Voters are concerned that Democrats are overreaching, particularly when it comes to the role of government,” Bolger said, underscoring Rendell’s point: “I think the suburbs tend to be the most volatile part of the electorate.”

Even as the nation’s stagnant economy touched off suburban unease, local issues also conspired to make the suburbs less-friendly ground for Democrats. In New Jersey’s gubernatorial election, 26 percent of voters said high property taxes were the most important issue to them, just 5 percent fewer than those who named the economy and jobs as their top concern.

Bergen County Republican Chairman Bob Yudin said New Jersey voters who typically gravitate toward Democrats gave Christie a second look because of local frustrations that piled up over the years the GOP was out of power in the state.

“They’re not a nuisance anymore. They’re oppressive. And everybody just started saying, ‘We can’t handle these kinds of taxes anymore,’” Yudin said. “The state of New Jersey, fiscally, financially, budget-wise, was in dire straits before the national meltdown.”

In New York, Spano and Suozzi also suffered from a backlash against the high cost of state and municipal government.

“The biggest thing locally was property taxes,” Suozzi told POLITICO last week. “The bottom line was, I’ve tried to be a leader on the property tax revolution, and I think I may have wound up being a victim of it.”

As the 2010 elections take shape, suburban districts like the ones where Democrats struggled this year will host some of the most competitive midterm races. Congressional Republicans have already drawn up a list of two dozen suburban House seats Democrats won in 2006 and 2008 that the GOP hopes to win back, including some in the very same territory Democrats lost in 2009.

Just a few miles outside Suozzi’s Nassau County, Rep. Tim Bishop has drawn a promising Republican challenger in businessman Randy Altschuler, who could give the Long Island Democrat his stiffest challenge since his first election in 2002.

In Sestak’s district — which the congressman won three years ago as Democrats outpaced Republicans in the suburbs by 2 points nationally, according to CNN exit polling — former Republican U.S. Attorney Pat Meehan is a leading candidate to seize the seat Sestak is vacating in order to run for Senate.

Elsewhere in the Northeastern and mid-Atlantic suburbs, both parties expect competitive races for suburban seats currently held by Democrats Jim Himes, who represents the Connecticut suburbs of New York City; John Adler, whose New Jersey district includes outlying Philadelphia suburbs; and John Hall, who represents parts of Westchester County, where Spano was ejected from office.

Rep. Steve Israel (D-N.Y.), who represents part of Nassau County in Congress, said 2009 is a warning sign that Democrats won’t be foolish enough to ignore.

“The lesson that Tom Suozzi teaches us is, you don’t take your election for granted. If you know the climate is challenging, and you know your polling is less than impressive, you’d better raise money to get your message out,” Israel said. “We lost badly in the suburbs in 1994, because we were just unprepared.”

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